System for indicating the pressure of the lubricant circulating in an internal combustion engine



F. K. H. NALLINGER SYSTEM FOR INDICATING THE PRESSURE OF THE LUBRICANTCIRCULATING IN AN INTERNAL COMBUSTION ENGINE Filed Oct. 5, 1960 Jan. 28,1964 .722 ven for FRIED /c/1 K H MALL/Na! 1 5) M l 9 A fro/ens 15 UnitedStates Patent 3,119,991 SYSTEM FOR INDICATING TI IE PRESSURE OF THELUBRHCANT CIRCULATING IN AN INTER- NAL CQMBUSTEQN ENGHNE Friedrich K. H.Nailinger, tuttgart, Germany, assignor to Daimler-BenzAlrtiengeseilsehatt, Starttgart lUnterturkheim, Germany Filed Oct. 3,1966, Bar. No. 69,121 Claims priority, application Germany Oct. 2, 19595 Claims. (Cl. 340-270) My invention relates to a system for indicatingthe pressure of the lubricant circulating in an internal combustionengine, more particularly in the engine of a motor vehicle, said systemincluding a signaling lamp for giving a signal indicative ofinsufiiciency of the lubricant pressure.

Prior systems of this type include switching means which is adjustableto a single definite minimum pressure and energizes the signaling lampas long as the pressure of the lubricant is lower than said minimumpressure. If this switching means is so adjusted that the minimumpressure is rather high, the lamp keeps burning, whenever the engine isidling or is operating within a lower range of its speed of operation,such lower range being of considerable extent. When the switching meansis so adjusted that the minimum pressure to which it responds is lower,the lamp will be turned off when a comparative low speed of operationhas been reached but will give no assurance that the lubricant pressureprevailing at a higher speed of operation is really sufiicient.

It is the object of my invention to provide an improved system of thetype described hereinabove which gives a reliable indication wheneverthe lubricant pressure is lower than a minimum limit which increaseswith rising speed of operation. More particularly, it is an object of myinvention to provide an improved system for indicating insufiiciency ofthe lubricant pressure where a low pressure sufiices for a slowoperation whereas a higher lubricant pressure is required for a fasteroperation of the engine.

More especially, it is an object of my invention to provide a system ofthis character which is simple and includes but a single indicating lampwhich will indicate insufficiency of the lubricant pressure over theentire range of speed of the engine in steps of smaller or largerextent.

Further objects of my invention will appear from a detailed descriptionof a preferred embodiment thereof illustrated in the accompanyingdrawing. It is to be understood, however, that my invention is in no wayrestricted to such details but is capable of numerous modificationswithin the scope of the appended claims and that the terms and phrasesused in such detailed description have been chosen for the purpose ofillustrating rather than that of restricting or limiting my invention.

In the accompanying drawing an electrical circuit dia gram of apreferred example of my novel indicating system is shown in which thesignaling lamp burns whenever the lubricant pressure is below a lowminimum during idling and at low speeds of operation and below a higherminimum during higher speeds of operation of the engine.

The system shown for indicating insufficiency of the pressure of thelubricant circulating in an internal combustion engine includes asignaling lamp 11 suitably disposed on the instrument panel of a motorvehicle, a plurality of contacts 12 and 13 selectively connectable tothe lamp 11, a current distributor 14 responsive to the speed ofoperation of the internal combustion engine 10 and connected to thecontacts 12 and 13 for selectively supplying current to at least one ofsaid contacts selected in dependence on the speed of operation andswitching means 15 which is connected to the lubricant circulatingsystem and responds to diiferent minimum pressures of the lubricant forselecting one of the contacts 12 and 13 in dependence on the pressureand for connecting it to the signaling lamp 11 for operating same.

In the embodiment shown the switching means 15 comprises a pair ofactuators 16 and 17 which respond to different minimum pressures and areindividually c0- ordinated to the contacts 12 and 13 for electricallycon meeting the same to the signaling lamp 11. As the two actuators aresimilar, it will suffice to describe one of them, to wit the actuator16. It comprises a cylinder connected by communicating pipes 18 and 19to the lubricant circulating system of the engine 10, a piston 20movable in the cylinder and a spring 21 inserted between one face of thepiston 20 and the end wall of the cylinder, whereas the other face ofthe piston 20 is subjected to the lubricant pressure. The chamberincluding the spring 21 is vented and the piston is provided with apiston rod 22 extending through the vented chamber and out of thecylinder and connected to a switch arm 23 which cooperates with thecontact 12 for connecting same with the lamp 11 through leads 24 and 25as long as the spring 21 keeps the switch arm 23 in engagement with thecontact 12 contrary to the pressure exerted upon the piston 20 by thelubricant. The spring is so adjusted by suitable means not shown that itwill keep the switch arm 23 in closed condition whenever the lubricantpressure is lower than a minimum pressure of e.g. 43 p.s.i. The actuator17 is so constructed and adjusted that it will keep its contact arm 26in closed condition as long as the lubricant pressure is below a minimumof 7 p.s.i.

In the embodiment shown the current distributor 14 is formed by a relayprovided with a winding 27, with an armature 28 and with a pair ofarmature contacts 29 and 31) for alternative engagement by the armature28 and a generator 31 coupled with the engine 10 and connected to thewinding 27 to supply current thereto. The members 28, 29 and 31 thusform a plurality of pairs of contacts comprised respectively by members28 and 29 and members 28 and 30. More particularly, the generator isprovided with a regulator element 32 which is grounded when thegenerator rests or operates at a low speed and at higher speeds ofoperation is supplied with a DC. voltage. The armature 28 engages thecontact 29 when the winding 27 is deenergized, and engages the contact13, when the winding 27 is energized. The contacts 12 and 13 wihch areselectively connectable to the lamp 11 by the switching means 15 areconnected to the armature contacts 29 and 30 by leads 33, and 34respectively. The system further comprises a source of currentdiagrammatically represented as a battery 35 which is connected to thearmature 28 through a switch 36 which preferably is the ignition switchof the engine 10 and a lead 37. The winding 27 has its upper terminalconnected to the lead 37 and its lower terminal connected by a lead 38to the regulator element 32 of the generator 31.

From the above it will appear that the armature contact 29 engaged bythe armature 28, when the winding 27 is deenergized, is connected withthe contact 12 which is connectable to the lamp 11 by the actuator whichis responsive to the higher minimum pressure of 43 p.s.i. of thelubricant.

It will be apparent from the foregoing description that the devicecomprises a first switch means comprising members 28, 29, 39, and asecond switch means comprising members 12, 23 and 13, 26.

The operation is as follows:

When the ignition switch 36 is opened, the engine 1 being at rest, theelements assume the position illustrated. When the ignition switch 36 isclosed, it closes a circuit including the elements 35, 36, 37, 2'7, 38and 32 and ground. The relay winding 27 included in this circuit isenergized and withdraws the armature 23 from the position shown intoengagement with the contact 39 which, in its turn, closes a circuitincluding the elements 35, 36, 37, 28, 30, 34, 13, 26, 24, and 11 andground. The indicating lamp 11 included in this circuit will burn thusindicating insufficiency of the lubricant pressure prevailing in theengine 10 which is still at rest.

As soon as the engine 10 has been started causing its lubricant pump tofeed lubricant to the lubrication points, the pressure produced by thepump will be conveyed through the pipes 18 and 19 to the actuators 16and 17. As long as the engine is idling, this pressure will be higherthan 7 psi. but lower than 43 psi. Therefore, the actuator 17 only willrespond to such pressure opening the switch arm 26 thereby interruptingthe circuit described hereinabove and turning off lamp 11.

When the speed of operation of the engine 10 increases above the idlingspeed, the generator 31 will produce a positive voltage counteractingthe flow of current through the relay winding 27 thus causing thearmature 28 to drop into engagement with contact 29. This establishes acircuit including the elements 35, 36, 37, 28, 29, 33, 12, 23, 24, 25and 11 and ground. In this circuit the lamp 11 will burn. As soon,however, as the lubricant pressure exceeds 43 psi. which is the minimumpressure required for a median range of speeds of operation of theengine 10, the actuator 16 will open switch arm 23 and thus turn olf thelamp 11 again.

From the above it will appear that in my novel system current will besupplied to the lamp in dependence on the speed of operation first byone of the actuators and then by the other actuator, the relay beingdeenergized, when the difference of potential between the battery andthe generator 31 decreases with increasing speed of operation of thegenerator causing the relay to be deenergized and to put the otheractuator in control of the signal lamp.

The embodiment described hereinabove is capable of numerousmodifications. Thus, the number of actuators need not be limited to two.Moreover, the switch arms 23 and 26 may be mounted for actuation by asingle actuator in response to different lubricant pressures. In mostcases, however, it will suffice to check the lubricant pressureprevailing in the lubricant system of the internal combustion engine intwo different ranges of speeds, for instance in an idling speed toascertain whether the lubricant system functions at all and in a higherspeed of operation to ascertain that the lubricant pressure is highenough for such higher speeds.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forth,together with other advantages which are obvious and which are inherentto the system.

While the invention has been described in connection with a preferredembodiment thereof, it will be understood that it is capable of furthermodification, and this application is intended to cover any variations,uses, or adaptations of the invention following, in general, theprinciples of the invention and including such departures from thepresent disclosure as come within known or cus tomary practice in theart to which the invention pertains, and as fall within the scope of theinvention or the limits of the appended claims.

What I claim is:

1. System for indicating the pressure of the lubricant circulating in aninternal combustion engine in which the minimum pressure requiredincreases with rising speed of operation, said system comprising asignaling lamp, said signaling lamp being in an unenergized conditionwhen the pressure of said lubricant is sufficient and in an cner gizedcondition when said pressure is insufiicient, a current distributorresponsive to the speed of operation of said internal combustion engine,said distributor comprising a plurality of pairs of contacts selectivelyconnectable to said lamp and means for selectively supplying current toat least one of said pairs of contacts in dependence on said speed, andswitching means comprising a plurality of actuators connected to thelubricant circulating system and being respectively responsive todilferent minimum pressures of said lubricant for selecting at least oneof said pairs of contacts in dependence on said pressure and forconnecting it to said signaling lamp for energizing same when at leastone of said minimum pressures is insufficient.

2. System as claimed in claim 1, in which said current distributorcomprises a relay provided with a winding, :1 first contact, a secondcontact and a conductive armature alternatively engageable with saidfirst contact and said second contact, said pairs of contactscomprising, firstly, said armature and said first contact, and secondly,said armature and second contact, and a generator coupled With saidengine and connected to said winding for supplying current thereto, saidsystem further comprising a source of current connected to saidarmature.

3. System for indicating the pressure of the lubricant circulating in aninternal combustion engine in which the minimum pressure requiredincreases with rising speed of operation, said system comprising asignalling lamp, said signalling lamp being in an unenergized conditionwhen the pressure of said lubricant is suflicient and being energizedwhen said pressure is insuificient, a pair of switch means connected tosaid lamp, a pair of actuators for said switch means connected to thelubricant circulating system of said engine and responsive to differentminimum pressure of said lubricant, a pair of contacts selectivelycontacted by said switch means, a current distributor relay providedwith a winding, with an armature and with two armature contacts forselective alternative engagement by said armature, one contact of saidpair of contacts being connected respectively to one of said arm turecontacts, a generator coupled to said engine for producing a voltagedepending upon said speed of operation, electrical means operativelyconnecting said voltage produced by said generator to said relay, asource of current and circuit means including an ignition switch forconnecting said source of current and said relay.

4. System as claimed in claim 3, in which that one of said two armaturecontacts engaged by said armature when said winding is deenergized isconnected with that contact of said pair of contacts which isconnectable to said lamp by that one of said actuators which isresponsive to the higher minimum pressure of said lubricant.

5. A means for indicating the pressure of the lubricant circulating inthe lubrication system of an internal combustion engine in which theminimum pressure required increases with the rising speed of operation,said means comprising a signalling lamp, circuit means connected to saidlamp, said circuit means including a generator driven by said engine andhaving an output proportional to the speed of operation of said engine,said circuit means further including switch means including twoswitches, control means for said switches opcratively connected to saidlubrication system, said control means including means for closing saidswitches, each of said switches being rc spectively closed by saidlast-named means in response to a lubricant pressure which is differentfor each of said switches, each said dilferent lubricant pressure beingbelow a difierent one of two respective selected minimum lubricantpressures, said circuit means further including e1ectrical means forcontrolling current supplied to said two switches, said electrical meanscomprising relay means including a pair of switch means responsive toenergization of said relay for closing a current circuit to one of saidtwo switches and a further pair of switch means responsive tode-energization of said relay for closing a current circuit to the otherof said two switches, a source of current selectively connectable toenergize said relay for closing said first-named pair of switch means,and means connecting said generator output to said relay forde-energizing said relay at a predetermined engine speed.

References Cited in the file of this patent UNITED STATES PATENTS

1. SYSTEM FOR INDICATING THE PRESSURE OF THE LUBRICANT CIRCULATING IN ANINTERNAL COMBUSTION ENGINE IN WHICH THE MINIMUM PRESSURE REQUIREDINCREASES WITH RISING SPEED OF OPERATION, SAID SYSTEM COMPRISING ASIGNALING LAMP, SAID SIGNALING LAMP BEING IN AN UNENERGIZED CONDITIONWHEN THE PRESSURE OF SAID LUBRICANT IS SUFFICIENT AND IN AN ENERGIZEDCONDITION WHEN SAID PRESSURE IS INSUFFICIENT, A CURRENT DISTRIBUTORRESPONSIVE TO THE SPEED OF OPERATION OF SAID INTERNAL COMBUSTION ENGINE,SAID DISTRIBUTOR COMPRISING A PLURALITY OF PAIRS OF CONTACTS SELECTIVELYCONNECTABLE TO SAID LAMP AND MEANS FOR SELECTIVELY SUPPLYING CURRENT TOAT LEAST ONE OF SAID PAIRS OF CONTACTS IN DEPENDENCE ON SAID SPEED, ANDSWITCHING MEANS COMPRISING A PLURALITY OF ACTUATORS CONNECTED TO THELUBRICANT CIRCULATING SYSTEM AND BEING RESPECTIVELY RESPONSIVE TODIFFERENT MINIMUM PRESSURES OF SAID LUBRICANT FOR SELECTING AT LEAST ONEOF SAID PAIRS OF CONTACTS IN DEPENDENCE ON SAID PRESSURE AND FORCONNECTING IT TO SAID SIGNALING LAMP FOR ENERGIZING SAME WHEN AT LEASTONE OF SAID MINIMUM PRESSURES IS INSUFFICIENT.